The overall objective of the Virology Core is to provide comprehensive virologic services, reagents, and biosafety level 3 facilities to members of the Columbia Rockefeller Center for AIDS Research, thereby facilitating their research on HIV/SIV, broadening the scope of their investigation, and promoting meaningful collaborations. Major core services will include HIV/SIV isolation, propagation and titration; 2) viral quantification by culture, bDNA amplification, PCR and RT-PCR; 3) characterization of viral phenotype with respect to growth kinetics, syncytium-inducing capacity, cellular tropism, and co-receptor usage; 4) analysis of HIV/SIV genotype; 5) phenotype and genotypic characterization of drug resistance; and 6) determination of host cell susceptibility to HIV and co-receptor expression. The core will also provide valuable reagents and cell lines to CFAR members, as well as the use of biosafety level 3 space. These services and the overall virologic expertise in the Core should enhance the research activities of the CR-CFAR.